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February 6, 2016

The big, bright constellation Orion scampers across the south on February evenings. Right now it’s high in the sky at nightfall, and due south around 9 o’clock. Look for its three-star belt, flanked by bright orange Betelgeuse to the upper left, and blue-white Rigel to the lower right.

In mythology, Orion was a hunter. And one of the creatures he hunted stands just below his feet. Lepus, the rabbit, contains a few moderately bright stars. Their proximity to Orion makes them easier to pick out.

The brightest is Alpha Leporis. And it really is a bright star — more than 30,000 times brighter than the Sun. In fact, it’s impressive just about any way you look at it. It’s far bigger and heavier than the Sun, and it faces a more impressive fate — it will explode as a supernova.

The star is only about 13 million years old, compared to four-and-a-half billion years for the Sun. But because it’s so much heavier, it “burns” through the fuel in its core much more quickly. As a result, it’s already nearing the end of its life. Changes in its core have caused it to puff up — big enough to extend out to the orbit of Mercury if it took the Sun’s place in the solar system.

Soon, it’ll get even bigger and brighter. Eventually, though, it will stop producing nuclear reactions in its core. The core will collapse, while the outer layers blast out into space — briefly giving the hunter a bit of a hotfoot.

We’ll have more about the rabbit tomorrow.

Script by Damond Benningfield, Copyright 2015


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